Auxiliary compound angle grinder for surface grinding machines



BAN 0 2,821,815 D ANGLE GRINDER FOR SURFACE GRINDING MACHINES Feb. 4, 1958 AUXILIARY COMPOUN 4 Sheets-Sheet 1 Filed April 18, 1956 H mm a mm M d E m M V. .B

G. KO AUXILIARY COMPOUND ANGLE GRINDER FOR SURFACE GRINDING MACHINES Filed April 18, 1956 4 Sheets-Sheet 2 FiE E INVENTOR.

6.60265 5/4NKO WZ/J ATT E VEY Feb. 4, 1958 821,815

G. BANKO AUXILIARY COMPOUND ANGLE GRINDER FOR SURFACE GRINDING MACHINES Filed April 18, 1956 4 Sheets-Sheet 3 INVENTOR. 65-0265 BAN/(O Feb. 4, 1958 G. BANKO 2,321,315

AUXILIARY COMPOUND ANGLE GRINDER FOR SURFACE GRINDINGAMACHINES Filed April 1a, 1956 I 4 Sheets-Sheet 4 'FIE-E YINVENTORI @EOEGE BAN/ 0 BY M 0p( United States Patent 2,821,815 AUXILIARY COMPOUND ANGLE GRINDER FOR SURFACE GRINDING MACHINES George Banko, Euclid, Ohio Application April 18, 1956, Serial No. 579,067 3 Claims. (CI. 51-34) This invention relates to grinding machines and particularly to a device for grinding compound angles.

Conducive to a better understanding of this invention, it may be well to point out that the grinding of a compound or rake angle on a conventional surface grinding machine is a very difiicult matter and requires a highly skilled workman.

In view of the fact that the grinding wheel remains in the same plane during the entire grinding process, the work piece must be tilted at difierent angles to achieve the specific compound angle desired.

As is well known to those skilled in the art, the tilting of a work piece to two angular positions often results in a cut that deviates considerably from the theoretical angle sought, due to a compounding factor. However, if the work piece is held stationary and the wheel tilted at the required compound angle, the angle may be cut at a single setting and be easily duplicated if dial readings are noted.

The primary object of this invention, therefore, is to provide an auxiliary compound angle grinder that may be easily attached to the spindle of a conventional surface grinder.

Another object is to provide a device of the type stated that is completely self-contained and operable off the power spindle of the surface grinder upon which it is mounted.

Still another object is to provide a compound angle grinder of the type stated whose grinding wheel passes over the work piece, while the work piece is held sta tionary.

A further object is to provide a compound angle grinder whose grinding wheel is mounted on a reciprocating tiltable table that may be easily set at the desired compound angle with reference to a stationary work piece.

Other objects are to provide a device of the type stated that is rugged in structure, simple in operation and fully adjustable as to stroke and angle of cut.

These and other objects of the invention will become apparent from a reading of the following specification and claims, together with the accompanying drawings, wherein:

Figure 1 is a perspective view of the auxiliary compound angle grinder that is the subject of this invention, showing it mounted on the spindle of a conventional surface grinder;

Figure 2 is a vertical sectional view of the compound angle grinder taken along the line and in the direction of the arrows 2-2 of the Figure 1;

Figure 3 is a bottom plan view of the stationary table;

Figure 4 is a top plan view of the reciprocating subtable;

Figure 5 is a top plan view of the assembled unit; and

Figure 6 is a cross sectional view of the split V-belt pulley taken along the line and in the direction of the arrows 6-6 of the Figure 5.

Referring more particularly to the drawings, there is seen in Figure 1 the auxiliary compound angle grinder that is the subject of this invention, broadly indicated by reference numeral 10, as it appears mounted on the spindle of a conventional surface grinder 30, outlined in broken lines.

The surface grinder broadly indicated by reference numeral 3i), is of the usual type having a reciprocating table 32 upon which is supported a vise 33 in which the work piece 34 is held. An upright post or column 31 supports the usual motor driven grinding wheel spindle 29 and its housing 67.

The compound angle grinder 10 is composed of three major parts, namely a bracket 11, a stationary table 15, and a reciprocating sub-table 49. The bracket 11 is mounted directly over the spindle housing 67 of the surface grinder 30 by means of a split collar 12 which is compressed around the spindle housing 67 by means of bolt 14. Before mounting the bracket 11 on the housing 67, a vertical line is scribed on the post 31 perpendicular to the center line of the spindle 29. This serves as a vertical guide mark or pointer for the angle scale 13 which extends upwardly of the bracket collar 12 for a purpose hereinafter to be disclosed. Two arcuate slots 16 and 17 are located on the bracket on either side of the collar 12. The bracket 11 has the shape of a segment of a circle with side edges 68 and 69 at 90 degrees to one another. A pivot point lug 21 is located at the apex of the bracket where the two sides 68 and 69 meet.

Reference numeral 15 indicates a rectangularly shaped stationary table which has a laterally extending lug 26 which is bored to receive a bolt 22. The table 15 is mounted on the bracket by means of the bolt 22 which passes through lugs 20 and 21 and acts as a point around which the table 15 may be pivoted relative to the bracket 11. The table 15 is also clamped to the bracket by means of bolts 18 and 19 which pass through the bracket slots 16 and 17 respectively, as is seen in Figures 1, 2 and 5.

The table 15 has wedge shaped parallel ways or tracks 23 and 24 on the lower face thereof, and a triangular shaped cavity 47 positioned therebetween, as seen in Figure 3.

A sub-table 49 is slidably mounted on the underside of table 15 by means of ways or tracks 50 and 51 which mate with the ways 24 and 23 respectively of table 15.

An auxiliary spindle 62 is journaled on the underside of subtable 49 cross-Wise thereof and parallel to the axis of the surface grinder spindle 29, as seen in Figures 1 and 2. The spindle 62 is supported on suitable ball bearings 63.

The spindle 62 has a worm 64. A V-pulley 65 is mounted on the spindle immediately behind a grinding wheel 66 which is mounted on the extreme end of the spindle 62. The pulley 65 is connected to the surface grinder spindle 29 by means of a V belt 48 which is stretched between the pulley 65 and a second pulley 36, mounted on the spindle 29, whose peculiar structure and function will be explained hereinafter.

Reference numeral 59 indicates a worm gear which is mounted on a vertically extending shaft 57 journaled in the table 49, as seen in Figure 2. The worm gear 59 is engaged with the spindle worm 64 and is loosely fitted to the shaft 57. The shaft 57 has a shoulder 58 against which the worm gear 59 may be pressed when the worm gear 59 is moved upward by pressure exerted against the clutch cone 60 by rotation of the thumb nut 61. In other words, the shaft 57 may be disconnected from the worm gear 59 by loosening the thumb nut 61, in which circumstance the worm gear may rot-ate free of the shaft 57. However, by tightening the thumb nut 61, the worm gear is brought into pressed engagement with the shaft 57 between the shoulder 58 and the clutch cone 60, thereby causing the shaft 57 to be rotated by the worm gear 59.

A crank arm 53 is mounted on the upper end of the shaft 57 and rotates in a cavity 52 cut in the upper face of the sub-table 49, as is seen most clearly in Figure 4. The crank arm 53 has a series of holes 54 spaced at different distances outwardly from its center of rotation.

A connecting rod 55 is pivotally connected atone end to the crank arm 53 by means of a pin 56 which is mounted in one of the crank arm holes 54'. The far end of the connecting rod 55 is pivotally connected to a pivot bolt 26 mounted in bore of the stationary table 15, as seen in Figure 2. i

In operation, the belt 48 is driven by the surface grinder spindle pulley 36 which, in turn causes rotation of. the auxiliary spindle 62. The grinding wheel 66 mounted on the spindle- 62 thereupon rotates. At the same time, the spindle worm 64- causes the worm. gear 59 to rotate and it, in turn, rotatesthe crank shaft 59 andcrank arm 53.

in view of the fact that the connecting rod 55 is anchored to the stationary table at one end, therotation of the crank arm 53 causes the sub table 49 to reciprocate relative to table 15 in accordance with well known me chanical laws. As a result, the grinding wheel 66 is reciprocated longitudinally of the stationary table 15 and will deliver a sweeping cut to anything placed immediately below its path of travel. A

It will be noted that the auxiliary spindle pulley 65 travels towardand away from the stationary surface grinder spindle pulley 36,as the sub-table 49 reciprocates. This alternately shortens and lengthens the space of the V belt 48 to a degree that would normally effect the proper oper ation of the machine and shorten the life of the belt. In order to provide for the belt length changes occuring, a novel construction for the pulley .36 has been devised.

The pulley 36 is made in two mating sections consisting of an inner hub 37 having a bore 39 into which the surface grinder spindle 29. is fitted. Thehub 37; is locked to the spindle 29 by means of a washer. 45and nut46. The inner hub 37 has a terminalfiange formed integral therewith and shaped as a /2 V, faced inward. A second or outer hub 41 is slidably fittedover. the inner hub 37 and is slidably locked thereto by means of a key 43, The outer hub 41 also has a terminal flange 42 shaped as a /2 V faced outward toward the flange 38.

Reference numeral 44 indicates a coil spring which is positioned around theouter hub 41 betweentheflange 42 and a lock ring 4Q.moun ted on the inner; end of the hub- 37. The spring actsto normally bias the flange42'against the flange 38 to form a shaped; slot therebetweenforthe receptionof the V belt 48 When the twopulleys 36 and65- are at their closest. position, the Vbelt 48will ride high in the V groove of pulley 36, as illustratedin full line in Figure 6.

When the pulleys are at their extreme distance apart, the belt 48 will be. pulled down in the groove to the position 48a, indicated indotted outline. At'the same time, the V belt will press against the groove sides moving the flange 42 and hub 41 longitudinallyof the hub 37 to the alternate position indicated in dotted outline by, reference numeral 42a. As the pulleys again approach one another, the belt 48. will loosen relieyingthepressure againsttfiange 42 which will be returned to its original position by the spring 44. Thus 'the. belt 48 willaiways remain centered in the pulley groove formed by the fianges38 and. 42: There will be no stretching: of the belt'48, which in effect is operating on even changing centers rather. than being subjected 'to destructive, distortion. Atthesame time, the tension onthe belt remainsconstantso that thereis no variation in power transmissionas the table 49 reciprocates.

It will now, be evident that; the auxiliary. compound angle grinder -1 0 just described is;.an entirely selfvcontained nttt ra iti h tt ayt sil e mnuutedm ism ulttsd 10a.

an existing surface grinding machine in a matter of minutes.

To set up the grinder to cut a compound angle, the following procedure is used.

The collar 12 is loosened and the whole assembly 10 is swung around the surface grinder spindle housing 67 within an arc of plus or minus 20 degrees with reference to the Zero point line 35, as indicated on the dial 13. The collar 12 is then. locked at the desired setting by means of the bolt 14. This tilts the table 15. at an angle to vertical. The table 15 may then bepivoted laterally plus or minus 10 degrees by loosening bolts 18, 19 and 22. The table is then pivoted around the bolt 22 to.eithe n plus or minus 10 degrees as indicated by the scales 27 and 28 respectively, scribedon the top of table 15, as is seen most clearly in Figure 5. After the required setting is obtained, the bolts 18, 19 and 22 are drawn up thereby locking the table in angular disposition with reference to the bracket 11.

The spindle 29 is then started and the power, transferred by means of the belt 48 to the auxiliary. spindle 62 which rotates the grinding wheel 66 mounted thereon and also causes the sub-table49, to reciprocate-melative to the stationary table 15 as describedhereinab ove.

The length of the stroke of the'table 49 is determined by which hole 54 in the crank arm 53 the connecting rod pin 56 is'anchored in. Those nearer the center of rotation provide a shorter stroke than thosefarther away. In the device illustrated the holes54 are so positioned that the stroke may be varied in steps of, 1 /2 ".-2"+.2 /z or 3".

The work piece 34 is mounted onthe surface grinder table 32 as-shown in Figure 1. The work piece 34: is held stationary and,the grinding wheel 66 iscarried across the work face by.- the reciprocating table 49 which holds the grinding wheel 66 at the desired compound angle to the work piece 34, As the grinding progresses, the work piece is fed toward the grinding wheel tov effect the depth of cutdesired.

When the wheel 66 is to be dressed, the worm gear 59 is disconnected from the crank shaft 57 byloosening the clutch thumb nut 61, The sub-table 49 will then beheld stationary. whil e the grinding wheel 66.rotates.

While the device has been illustrated as being adapted to grind compoundangles varying between plus or minus 2 0 degrees in one direction and- 10 degreesin another direction, it is to be understood; that other; degrees of angular setting may be provided within wide limits;

It. will now, be clearthat there is: provided a device which accomplishes, the objectives heretofore set forth;

While the. invention has: been disclosed in; its preferred; form, it is to be understood that the; specific; embodiment thereof as described and illustrated herein is not to be considered; in. a limited sense i as there; may be other; forms or modifications of the invention which should also be construed toico me within the scope of the-appended claims.

1 claim:

1. In combination with a surface grinding machinep n and s ins fo nuxi iary pmp u ang grinder, comprising a bracket adapted to be mounted on the surface grinder, spindle housing, includinga stationary table, means for holding said stationary table -in adjusted angular positions, both verticallyandglaterally with referet0v the i l Pla e: f he fa rin er: pin le, pulley mounted on thesnrface-grinder spindle,- a-subflablc id ount d. Qnthe und s de f aidt tatipn r-yta l an auxiliary spindle journaled 1on said sub-tableimaplane substantially parallel to the surface grinder spindle, and

nc i a. r d n wh el nu ynan rm, iv ng beltconnecting the surface grinder andxauxiliary spindle p y a a k haf i r a edt t hesuhe hl t p pendicular to the upper face thereof and including. a worm;

e ng ged; h he. aty p nd e. Q mi. a; r n

mounted on said crank shaft and rotatable therewith, and a connecting rod pivotally connected at one end to the stationary table and at the other end to the crank arm, said connecting rod acting to reciprocate the sub-table'longitudinally of the stationary table upon rotation of the crank arm.

2. In combination with a surface grinding machine spindle and housing therefor, an auxiliary compound angle grinder, comprising a bracket including a contractable collar and a stationary table swivelly mounted below the collar, the bracket collar being adapted to receive the surface grinder spindle housing therein and including locking means for positioning said bracket in adjusted angular radial relation to said surface grinder spindle, means for positioning said stationary table in adjusted angular lateral relation to said collar, a pulley mounted on the surface grinder spindle, a sub-table slidably mounted on the under side of said stationary table, an auxiliary spindle journaled on said sub-table in a plane substantially parallel to the surface grinder spindle, and including a grinding wheel, pulley and worm, a driving belt connecting the surface grinder and auxiliary spindle pulleys, a crank shaft journaled in the sub-table, perpendicular to the upper face thereof and including a worm gear engaged with the auxiliary spindle worm, a crank mounted on said crank shaft and rotatable therewith, and a connecting rod pivotally connected at one end to the stationary table and at the other end to the crank arm, said connecting rod acting to reciprocate the sub-table longitudinally of the stationary table upon rotation of the crank arm.

3. A device as defined in claim 2 and further characterized by the surface grinder spindle pulley being composed of two nested hubs having complementary /2 V flanges faced toward one another, the inner of said hubs being mounted on the surface grinder spindle, the outer of said hubs being slidably mounted on the inner hub, and spring means urging said outer hub flange toward the inner hub flange to form a V groove therebetween for the retention of a V belt therein.

References Cited in the file of this patent UNITED STATES PATENTS 292,229 Johnson Jan. 22, 1884 1,832,997 Reid Nov. 24, 1931 FOREIGN PATENTS 853,748 France Dec. 7, 1939 

